In private communication systems including multiple private branch exchanges (PBXs), a uniform numbering plan (UNP) feature gives a user the ability to call any other designated party on the network by dialing a single unique station number. Typically, the called number includes an access code digit, a location code and a station code or number to establish a call. The location code includes up to three digits to designate the PBX where the call is to terminate, while the station number may be two, three or four digits to identify the called station at the called PBX. Existing UNP network features require the length of the location code and station number to be fixed. Thus, if one PBX requires four digits for its station address, then four digits must be utilized for all the. station addresses for any PBX on the network.
Customers desire an abbreviated dialing arrangement to reduce the number of dialed digits, dialing errors and signaling time.